Posted by Wayne Parham [ 64.216.179.54 ] on December 04, 2004 at 14:55:13:

In Reply to: Need schematic -- RCA posted by mark williams on December 03, 2004 at 21:39:11:

You probably need power supply capacitors. Look for capacitors inside the radio with values around 8uF to 20uF. You'll probably find two or three; Replace them with polypropylene 250v caps and the hum will probably go away.

I found a schematic that may be for your radio on Rider volume 14. It has 35Z5, 50L6, 12SA7, 12SK7 and 12SQ7 tubes. That was a very common tube set for RCA radios. I have a couple of chassis like those myself. One of mine was just like yours when I got it - Working but with a lot of hum. I replaced the power supply caps and it was much quieter.

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